Definition of proto- in English:

proto-

(also prot-)

combining form

  • 1Original; primitive.

    ‘prototherian’
    ‘prototype’
    ancient, earliest, first, prehistoric, antediluvian, antique, primordial, primeval, primal, primary, lower, original, proto-, ur-
    View synonyms
    1. 1.1 First; anterior; relating to a precursor.
      ‘protomartyr’
      ‘protozoan’

Origin

From Greek prōtos first.

Pronunciation:

proto-

/ˈprōdō/